From fdd780d0a26070e59fe2c3690a776aad25227756 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Tue, 30 Oct 2018 13:26:15 -0400 Subject: [PATCH] Cramfs: fix abad comparison when wrap-arounds occur commit 672ca9dd13f1aca0c17516f76fc5b0e8344b3e46 upstream. It is possible for corrupted filesystem images to produce very large block offsets that may wrap when a length is added, and wrongly pass the buffer size test. Reported-by: Anatoly Trosinenko Signed-off-by: Nicolas Pitre Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/cramfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index 7919967488cb..011c6f53dcda 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -186,7 +186,8 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i continue; blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT; blk_offset += offset; - if (blk_offset + len > BUFFER_SIZE) + if (blk_offset > BUFFER_SIZE || + blk_offset + len > BUFFER_SIZE) continue; return read_buffers[i] + blk_offset; }